jdk/src/share/native/sun/java2d/cmm/lcms/cmswtpnt.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

// This file is available under and governed by the GNU General Public
// License version 2 only, as published by the Free Software Foundation.
// However, the following notice accompanied the original version of this
// file:
//
//
//  Little cms
//  Copyright (C) 1998-2006 Marti Maria
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#include "lcms.h"

// Uncomment this line if you want lcms to use the black point tag in profile,
// if commented, lcms will compute the black point by its own.
// It is safer to leve it commented out
// #define HONOR_BLACK_POINT_TAG

// Conversions

void LCMSEXPORT cmsXYZ2xyY(LPcmsCIExyY Dest, const cmsCIEXYZ* Source)
{
       double ISum;

       ISum = 1./(Source -> X + Source -> Y + Source -> Z);

       Dest -> x = (Source -> X) * ISum;
       Dest -> y = (Source -> Y) * ISum;
       Dest -> Y = Source -> Y;
}


void LCMSEXPORT cmsxyY2XYZ(LPcmsCIEXYZ Dest, const cmsCIExyY* Source)
{

        Dest -> X = (Source -> x / Source -> y) * Source -> Y;
        Dest -> Y = Source -> Y;
        Dest -> Z = ((1 - Source -> x - Source -> y) / Source -> y) * Source -> Y;
}



// Obtains WhitePoint from Temperature

BOOL LCMSEXPORT cmsWhitePointFromTemp(int TempK, LPcmsCIExyY WhitePoint)
{
       double x, y;
       double T, T2, T3;
       // double M1, M2;


       // No optimization provided.

       T = TempK;
       T2 = T*T;            // Square
       T3 = T2*T;           // Cube

       // For correlated color temperature (T) between 4000K and 7000K:

       if (T >= 4000. && T <= 7000.)
       {
              x = -4.6070*(1E9/T3) + 2.9678*(1E6/T2) + 0.09911*(1E3/T) + 0.244063;
       }
       else
              // or for correlated color temperature (T) between 7000K and 25000K:

       if (T > 7000.0 && T <= 25000.0)
       {
              x = -2.0064*(1E9/T3) + 1.9018*(1E6/T2) + 0.24748*(1E3/T) + 0.237040;
       }
       else {
              cmsSignalError(LCMS_ERRC_ABORTED, "cmsWhitePointFromTemp: invalid temp");
              return FALSE;
              }

       // Obtain y(x)

       y = -3.000*(x*x) + 2.870*x - 0.275;

       // wave factors (not used, but here for futures extensions)

       // M1 = (-1.3515 - 1.7703*x + 5.9114 *y)/(0.0241 + 0.2562*x - 0.7341*y);
       // M2 = (0.0300 - 31.4424*x + 30.0717*y)/(0.0241 + 0.2562*x - 0.7341*y);



       // Fill WhitePoint struct

       WhitePoint -> x = x;
       WhitePoint -> y = y;
       WhitePoint -> Y = 1.0;

       return TRUE;
}

// Build a White point, primary chromas transfer matrix from RGB to CIE XYZ
// This is just an approximation, I am not handling all the non-linear
// aspects of the RGB to XYZ process, and assumming that the gamma correction
// has transitive property in the tranformation chain.
//
// the alghoritm:
//
//            - First I build the absolute conversion matrix using
//              primaries in XYZ. This matrix is next inverted
//            - Then I eval the source white point across this matrix
//              obtaining the coeficients of the transformation
//            - Then, I apply these coeficients to the original matrix


BOOL LCMSEXPORT cmsBuildRGB2XYZtransferMatrix(LPMAT3 r, LPcmsCIExyY WhitePt,
                                            LPcmsCIExyYTRIPLE Primrs)
{
        VEC3 WhitePoint, Coef;
        MAT3 Result, Primaries;
        double xn, yn;
        double xr, yr;
        double xg, yg;
        double xb, yb;


        xn = WhitePt -> x;
        yn = WhitePt -> y;
        xr = Primrs -> Red.x;
        yr = Primrs -> Red.y;
        xg = Primrs -> Green.x;
        yg = Primrs -> Green.y;
        xb = Primrs -> Blue.x;
        yb = Primrs -> Blue.y;


        // Build Primaries matrix

        VEC3init(&Primaries.v[0], xr,        xg,         xb);
        VEC3init(&Primaries.v[1], yr,        yg,         yb);
        VEC3init(&Primaries.v[2], (1-xr-yr), (1-xg-yg),  (1-xb-yb));


        // Result = Primaries ^ (-1) inverse matrix

        if (!MAT3inverse(&Primaries, &Result))
                        return FALSE;


        VEC3init(&WhitePoint, xn/yn, 1.0, (1.0-xn-yn)/yn);

        // Across inverse primaries ...

        MAT3eval(&Coef, &Result, &WhitePoint);

        // Give us the Coefs, then I build transformation matrix

        VEC3init(&r -> v[0], Coef.n[VX]*xr,          Coef.n[VY]*xg,          Coef.n[VZ]*xb);
        VEC3init(&r -> v[1], Coef.n[VX]*yr,          Coef.n[VY]*yg,          Coef.n[VZ]*yb);
        VEC3init(&r -> v[2], Coef.n[VX]*(1.0-xr-yr), Coef.n[VY]*(1.0-xg-yg), Coef.n[VZ]*(1.0-xb-yb));


        return TRUE;
}



// Compute chromatic adaptation matrix using Chad as cone matrix

static
void ComputeChromaticAdaptation(LPMAT3 Conversion,
                                LPcmsCIEXYZ SourceWhitePoint,
                                LPcmsCIEXYZ DestWhitePoint,
                                LPMAT3 Chad)

{

        MAT3 Chad_Inv;
        VEC3 ConeSourceXYZ, ConeSourceRGB;
        VEC3 ConeDestXYZ, ConeDestRGB;
        MAT3 Cone, Tmp;


        Tmp = *Chad;
        MAT3inverse(&Tmp, &Chad_Inv);

        VEC3init(&ConeSourceXYZ, SourceWhitePoint -> X,
                                 SourceWhitePoint -> Y,
                                 SourceWhitePoint -> Z);

        VEC3init(&ConeDestXYZ,   DestWhitePoint -> X,
                                 DestWhitePoint -> Y,
                                 DestWhitePoint -> Z);

        MAT3eval(&ConeSourceRGB, Chad, &ConeSourceXYZ);
        MAT3eval(&ConeDestRGB,   Chad, &ConeDestXYZ);

        // Build matrix

        VEC3init(&Cone.v[0], ConeDestRGB.n[0]/ConeSourceRGB.n[0],    0.0,  0.0);
        VEC3init(&Cone.v[1], 0.0,   ConeDestRGB.n[1]/ConeSourceRGB.n[1],   0.0);
        VEC3init(&Cone.v[2], 0.0,   0.0,   ConeDestRGB.n[2]/ConeSourceRGB.n[2]);


        // Normalize
        MAT3per(&Tmp, &Cone, Chad);
        MAT3per(Conversion, &Chad_Inv, &Tmp);

}


// Returns the final chrmatic adaptation from illuminant FromIll to Illuminant ToIll
// The cone matrix can be specified in ConeMatrix. If NULL, Bradford is assumed

BOOL cmsAdaptationMatrix(LPMAT3 r, LPMAT3 ConeMatrix, LPcmsCIEXYZ FromIll, LPcmsCIEXYZ ToIll)
{
     MAT3 LamRigg   = {{ // Bradford matrix
                      {{  0.8951,  0.2664, -0.1614 }},
                      {{ -0.7502,  1.7135,  0.0367 }},
                      {{  0.0389, -0.0685,  1.0296 }}
                      }};


      if (ConeMatrix == NULL)
            ConeMatrix = &LamRigg;

      ComputeChromaticAdaptation(r, FromIll, ToIll, ConeMatrix);
      return TRUE;

}

// Same as anterior, but assuming D50 destination. White point is given in xyY

BOOL cmsAdaptMatrixToD50(LPMAT3 r, LPcmsCIExyY SourceWhitePt)
{
        cmsCIEXYZ Dn;
        MAT3 Bradford;
        MAT3 Tmp;

        cmsxyY2XYZ(&Dn, SourceWhitePt);

        cmsAdaptationMatrix(&Bradford, NULL, &Dn, cmsD50_XYZ());

        Tmp = *r;
        MAT3per(r, &Bradford, &Tmp);

        return TRUE;
}


// Same as anterior, but assuming D50 source. White point is given in xyY

BOOL cmsAdaptMatrixFromD50(LPMAT3 r, LPcmsCIExyY DestWhitePt)
{
        cmsCIEXYZ Dn;
        MAT3 Bradford;
        MAT3 Tmp;

        cmsxyY2XYZ(&Dn, DestWhitePt);

        cmsAdaptationMatrix(&Bradford, NULL, cmsD50_XYZ(), &Dn);

        Tmp = *r;
        MAT3per(r, &Bradford, &Tmp);

        return TRUE;
}


// Adapts a color to a given illuminant. Original color is expected to have
// a SourceWhitePt white point.

BOOL LCMSEXPORT cmsAdaptToIlluminant(LPcmsCIEXYZ Result,
                                     LPcmsCIEXYZ SourceWhitePt,
                                     LPcmsCIEXYZ Illuminant,
                                     LPcmsCIEXYZ Value)
{
        MAT3 Bradford;
        VEC3 In, Out;

        // BradfordLamRiggChromaticAdaptation(&Bradford, SourceWhitePt, Illuminant);

        cmsAdaptationMatrix(&Bradford, NULL, SourceWhitePt, Illuminant);

        VEC3init(&In, Value -> X, Value -> Y, Value -> Z);
        MAT3eval(&Out, &Bradford, &In);

        Result -> X = Out.n[0];
        Result -> Y = Out.n[1];
        Result -> Z = Out.n[2];

        return TRUE;
}



typedef struct {

    double mirek;  // temp (in microreciprocal kelvin)
    double ut;     // u coord of intersection w/ blackbody locus
    double vt;     // v coord of intersection w/ blackbody locus
    double tt;     // slope of ISOTEMPERATURE. line

    } ISOTEMPERATURE,FAR* LPISOTEMPERATURE;

static ISOTEMPERATURE isotempdata[] = {
//  {Mirek, Ut,       Vt,      Tt      }
    {0,     0.18006,  0.26352,  -0.24341},
    {10,    0.18066,  0.26589,  -0.25479},
    {20,    0.18133,  0.26846,  -0.26876},
    {30,    0.18208,  0.27119,  -0.28539},
    {40,    0.18293,  0.27407,  -0.30470},
    {50,    0.18388,  0.27709,  -0.32675},
    {60,    0.18494,  0.28021,  -0.35156},
    {70,    0.18611,  0.28342,  -0.37915},
    {80,    0.18740,  0.28668,  -0.40955},
    {90,    0.18880,  0.28997,  -0.44278},
    {100,   0.19032,  0.29326,  -0.47888},
    {125,   0.19462,  0.30141,  -0.58204},
    {150,   0.19962,  0.30921,  -0.70471},
    {175,   0.20525,  0.31647,  -0.84901},
    {200,   0.21142,  0.32312,  -1.0182 },
    {225,   0.21807,  0.32909,  -1.2168 },
    {250,   0.22511,  0.33439,  -1.4512 },
    {275,   0.23247,  0.33904,  -1.7298 },
    {300,   0.24010,  0.34308,  -2.0637 },
    {325,   0.24702,  0.34655,  -2.4681 },
    {350,   0.25591,  0.34951,  -2.9641 },
    {375,   0.26400,  0.35200,  -3.5814 },
    {400,   0.27218,  0.35407,  -4.3633 },
    {425,   0.28039,  0.35577,  -5.3762 },
    {450,   0.28863,  0.35714,  -6.7262 },
    {475,   0.29685,  0.35823,  -8.5955 },
    {500,   0.30505,  0.35907,  -11.324 },
    {525,   0.31320,  0.35968,  -15.628 },
    {550,   0.32129,  0.36011,  -23.325 },
    {575,   0.32931,  0.36038,  -40.770 },
    {600,   0.33724,  0.36051, -116.45  }
};

#define NISO sizeof(isotempdata)/sizeof(ISOTEMPERATURE)


// Robertson's method

static
double Robertson(LPcmsCIExyY v)
{
    int j;
    double us,vs;
    double uj,vj,tj,di,dj,mi,mj;
    double Tc = -1, xs, ys;

    di = mi = 0;
    xs = v -> x;
    ys = v -> y;

    // convert (x,y) to CIE 1960 (u,v)

    us = (2*xs) / (-xs + 6*ys + 1.5);
    vs = (3*ys) / (-xs + 6*ys + 1.5);


    for (j=0; j < NISO; j++) {

        uj = isotempdata[j].ut;
        vj = isotempdata[j].vt;
        tj = isotempdata[j].tt;
        mj = isotempdata[j].mirek;

        dj = ((vs - vj) - tj * (us - uj)) / sqrt(1 + tj*tj);



        if ((j!=0) && (di/dj < 0.0)) {
            Tc = 1000000.0 / (mi + (di / (di - dj)) * (mj - mi));
            break;
        }

        di = dj;
        mi = mj;
    }


    if (j == NISO) return -1;
    return Tc;
}



static
BOOL InRange(LPcmsCIExyY a, LPcmsCIExyY b, double tolerance)
{
       double dist_x, dist_y;

       dist_x = fabs(a->x - b->x);
       dist_y = fabs(a->y - b->y);

       return (tolerance >= dist_x * dist_x + dist_y * dist_y);

}


typedef struct {
                char Name[30];
                cmsCIExyY Val;

              } WHITEPOINTS,FAR *LPWHITEPOINTS;

static
int FromD40toD150(LPWHITEPOINTS pts)
{
       int i, n;

       n = 0;
       for (i=40; i < 150; i ++)
       {
              sprintf(pts[n].Name, "D%d", i);
              cmsWhitePointFromTemp((int) (i*100.0), &pts[n].Val);
              n++;
       }

   return n;
}


void _cmsIdentifyWhitePoint(char *Buffer, LPcmsCIEXYZ WhitePt)
{
       int i, n;
       cmsCIExyY Val;
       double T;
       WHITEPOINTS SomeIlluminants[140] = {

                                   {"CIE illuminant A", {0.4476, 0.4074, 1.0}},
                                   {"CIE illuminant C", {0.3101, 0.3162, 1.0}},
                                   {"D65 (daylight)",   {0.3127, 0.3291, 1.0}},
                                   };

              n = FromD40toD150(&SomeIlluminants[3]) + 3;

              cmsXYZ2xyY(&Val, WhitePt);

              Val.Y = 1.;
              for (i=0; i < n; i++)
              {

                            if (InRange(&Val, &SomeIlluminants[i].Val, 0.000005))
                            {
                                strcpy(Buffer, "WhitePoint : ");
                                strcat(Buffer, SomeIlluminants[i].Name);
                                return;
                            }
              }

              T = Robertson(&Val);

              if (T > 0)
                sprintf(Buffer, "White point near %dK", (int) T);
              else
              {
              sprintf(Buffer, "Unknown white point (X:%1.2g, Y:%1.2g, Z:%1.2g)",
                                          WhitePt -> X, WhitePt -> Y, WhitePt -> Z);

              }

}


// Use darker colorant to obtain black point

static
int BlackPointAsDarkerColorant(cmsHPROFILE hInput,
                               int Intent,
                               LPcmsCIEXYZ BlackPoint,
                               DWORD dwFlags)
{
    WORD *Black, *White;
    cmsHTRANSFORM xform;
    icColorSpaceSignature Space;
    int nChannels;
    DWORD dwFormat;
    cmsHPROFILE hLab;
    cmsCIELab  Lab;
    cmsCIEXYZ  BlackXYZ, MediaWhite;

    // If the profile does not support input direction, assume Black point 0

    if (!cmsIsIntentSupported(hInput, Intent, LCMS_USED_AS_INPUT)) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
        return 0;
    }


    // Try to get black by using black colorant

    Space = cmsGetColorSpace(hInput);

    if (!_cmsEndPointsBySpace(Space, &White, &Black, &nChannels)) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
        return 0;
    }

    dwFormat = CHANNELS_SH(nChannels)|BYTES_SH(2);

    hLab = cmsCreateLabProfile(NULL);

    xform = cmsCreateTransform(hInput, dwFormat,
                                hLab, TYPE_Lab_DBL, Intent, cmsFLAGS_NOTPRECALC);


    cmsDoTransform(xform, Black, &Lab, 1);

    // Force it to be neutral, clip to max. L* of 50

    Lab.a = Lab.b = 0;
    if (Lab.L > 50) Lab.L = 50;

    cmsCloseProfile(hLab);
    cmsDeleteTransform(xform);

    cmsLab2XYZ(NULL, &BlackXYZ, &Lab);

    if (Intent == INTENT_ABSOLUTE_COLORIMETRIC) {

        *BlackPoint = BlackXYZ;
    }
    else {

        if (!(dwFlags & LCMS_BPFLAGS_D50_ADAPTED)) {

            cmsTakeMediaWhitePoint(&MediaWhite, hInput);
            cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &BlackXYZ);
        }
        else
            *BlackPoint = BlackXYZ;
    }

    return 1;
}


// Get a black point of output CMYK profile, discounting any ink-limiting embedded
// in the profile. Fou doing that, use perceptual intent in input direction:
// Lab (0, 0, 0) -> [Perceptual] Profile -> CMYK -> [Rel. colorimetric] Profile -> Lab

static
int BlackPointUsingPerceptualBlack(LPcmsCIEXYZ BlackPoint,
                                   cmsHPROFILE hProfile,
                                   DWORD dwFlags)
{
    cmsHTRANSFORM hPercLab2CMYK, hRelColCMYK2Lab;
    cmsHPROFILE hLab;
    cmsCIELab LabIn, LabOut;
    WORD CMYK[MAXCHANNELS];
    cmsCIEXYZ  BlackXYZ, MediaWhite;


     if (!cmsIsIntentSupported(hProfile, INTENT_PERCEPTUAL, LCMS_USED_AS_INPUT)) {

        BlackPoint -> X = BlackPoint ->Y = BlackPoint -> Z = 0.0;
        return 0;
    }

    hLab = cmsCreateLabProfile(NULL);

    hPercLab2CMYK  = cmsCreateTransform(hLab, TYPE_Lab_DBL,
                                        hProfile, TYPE_CMYK_16,
                                        INTENT_PERCEPTUAL, cmsFLAGS_NOTPRECALC);

    hRelColCMYK2Lab = cmsCreateTransform(hProfile, TYPE_CMYK_16,
                                         hLab, TYPE_Lab_DBL,
                                         INTENT_RELATIVE_COLORIMETRIC, cmsFLAGS_NOTPRECALC);

    LabIn.L = LabIn.a = LabIn.b = 0;

    cmsDoTransform(hPercLab2CMYK, &LabIn, CMYK, 1);
    cmsDoTransform(hRelColCMYK2Lab, CMYK, &LabOut, 1);

    if (LabOut.L > 50) LabOut.L = 50;
    LabOut.a = LabOut.b = 0;

    cmsDeleteTransform(hPercLab2CMYK);
    cmsDeleteTransform(hRelColCMYK2Lab);
    cmsCloseProfile(hLab);

    cmsLab2XYZ(NULL, &BlackXYZ, &LabOut);

    if (!(dwFlags & LCMS_BPFLAGS_D50_ADAPTED)){
            cmsTakeMediaWhitePoint(&MediaWhite, hProfile);
            cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &BlackXYZ);
    }
    else
            *BlackPoint = BlackXYZ;

    return 1;

}


// Get Perceptual black of v4 profiles.
static
int GetV4PerceptualBlack(LPcmsCIEXYZ BlackPoint, cmsHPROFILE hProfile, DWORD dwFlags)
{
        if (dwFlags & LCMS_BPFLAGS_D50_ADAPTED) {

            BlackPoint->X = PERCEPTUAL_BLACK_X;
            BlackPoint->Y = PERCEPTUAL_BLACK_Y;
            BlackPoint->Z = PERCEPTUAL_BLACK_Z;
        }
        else {

            cmsCIEXYZ D50BlackPoint, MediaWhite;

            cmsTakeMediaWhitePoint(&MediaWhite, hProfile);
            D50BlackPoint.X = PERCEPTUAL_BLACK_X;
            D50BlackPoint.Y = PERCEPTUAL_BLACK_Y;
            D50BlackPoint.Z = PERCEPTUAL_BLACK_Z;
            cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &D50BlackPoint);
        }


        return 1;
}


// This function shouldn't exist at all -- there is such quantity of broken
// profiles on black point tag, that we must somehow fix chromaticity to
// avoid huge tint when doing Black point compensation. This function does
// just that. If BP is specified, then forces it to neutral and uses only L
// component. If does not exist, computes it by taking 400% of ink or RGB=0 This
// works well on relative intent and is undefined on perceptual & saturation.
// However, I will support all intents for tricking & trapping.


int cmsDetectBlackPoint(LPcmsCIEXYZ BlackPoint, cmsHPROFILE hProfile, int Intent, DWORD dwFlags)
{

    // v4 + perceptual & saturation intents does have its own black point

    if ((cmsGetProfileICCversion(hProfile) >= 0x4000000) &&
        (Intent == INTENT_PERCEPTUAL || Intent == INTENT_SATURATION)) {

       // Matrix shaper share MRC & perceptual intents

       if (_cmsIsMatrixShaper(hProfile))
           return BlackPointAsDarkerColorant(hProfile, INTENT_RELATIVE_COLORIMETRIC, BlackPoint, cmsFLAGS_NOTPRECALC);

       // Get fixed value
       return GetV4PerceptualBlack(BlackPoint, hProfile, dwFlags);
    }


#ifdef HONOR_BLACK_POINT_TAG

    // v2, v4 rel/abs colorimetric
    if (cmsIsTag(hProfile, icSigMediaBlackPointTag) &&
                    Intent == INTENT_RELATIVE_COLORIMETRIC) {

        cmsCIEXYZ BlackXYZ, UntrustedBlackPoint, TrustedBlackPoint, MediaWhite;
        cmsCIELab Lab;

             // If black point is specified, then use it,

             cmsTakeMediaBlackPoint(&BlackXYZ, hProfile);
             cmsTakeMediaWhitePoint(&MediaWhite, hProfile);

             // Black point is absolute XYZ, so adapt to D50 to get PCS value

             cmsAdaptToIlluminant(&UntrustedBlackPoint, &MediaWhite, cmsD50_XYZ(), &BlackXYZ);

             // Force a=b=0 to get rid of any chroma

             cmsXYZ2Lab(NULL, &Lab, &UntrustedBlackPoint);
             Lab.a = Lab.b = 0;
             if (Lab.L > 50) Lab.L = 50; // Clip to L* <= 50

             cmsLab2XYZ(NULL, &TrustedBlackPoint, &Lab);

             // Return BP as D50 relative or absolute XYZ (depends on flags)

             if (!(dwFlags & LCMS_BPFLAGS_D50_ADAPTED))
                    cmsAdaptToIlluminant(BlackPoint, cmsD50_XYZ(), &MediaWhite, &TrustedBlackPoint);
             else
                    *BlackPoint = TrustedBlackPoint;

             return 1;
    }

#endif

    // If output profile, discount ink-limiting

    if (Intent == INTENT_RELATIVE_COLORIMETRIC &&
            (cmsGetDeviceClass(hProfile) == icSigOutputClass) &&
            (cmsGetColorSpace(hProfile) == icSigCmykData))
                return BlackPointUsingPerceptualBlack(BlackPoint, hProfile, dwFlags);

    // Nope, compute BP using current intent.

    return BlackPointAsDarkerColorant(hProfile, Intent, BlackPoint, dwFlags);

}